JPH0799150A - Transmission mask for charged beam exposure and manufacture thereof - Google Patents

Abstract

PURPOSE:To reduce the number of manufacturing processes and to shorten the time required for manufacture by forming an etching stop layer of an Si substrate after a pattern part to be transmission holes is formed in the surface of the Si substrate. CONSTITUTION:An Si pattern of a part to be transmission holes 3 for a charged beam is formed by etching an Si substrate 1, using a resist pattern 2 formed on the surface of the Si substrate as a mask. Next, the whole surface of the Si substrate 1 wherein the transmission holes 3 are formed is covered with a thin film 4. Subsequently, the thin film 4 is etched by using an opening resist pattern 5 formed in a part to be an opening of a transmission mask on the opposite surface side of the Si substrate l, as the mask. Then, the Si substrate 1 is etched with the part of the thin film 4 of an opening pattern for etching protection used as an etching mask. The etching of the part facing the transmission hole 3 stops at a place where it reaches the thin film 4 for stopping the etching which is formed in the bottom part of the transmission hole 3 in the preceding process. By removing the thin film left in the part of the transmission hole 3 thereafter, a transmission mask structure 6 is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged beam (electron beam or charged beam) which is used for various purposes such as manufacturing of fine patterns including manufacturing of semiconductor integrated circuits such as LSI, VLSI, etc. and modification of materials. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to (particle beam) exposure, and more specifically, to a transmission mask having through holes for charged beam exposure and a method for manufacturing the same.

[0002]

2. Description of the Related Art A typical method of manufacturing a conventional transmission mask will be described with reference to FIG. First, as shown in FIG. 3A, an Si substrate is prepared by bonding a supporting Si substrate on which an insulating layer is formed by thermal oxidation or the like and an upper Si substrate by thermal bonding or the like. To a thin thickness by polishing. Next, as shown in FIG. 2B, a SiN film or the like is deposited on the front and back surfaces of the bonded Si substrate to form a mask layer, and then, as shown in FIG. The mask layer on the back surface of the substrate is etched to form openings.

Next, as shown in FIG. 2D, the upper Si substrate is etched to form a transmission hole, and then, as shown in FIG. 2E, the mask Si layer is used as a protective layer to support the opening Si substrate. Is etched with a KOH aqueous solution or the like to form an opening. After that, the mask layer is removed and the insulating layer is etched to form a transmission hole as shown in FIG.
Finally, as shown in FIG. 3G, a conductive layer is formed on the upper Si substrate by sputtering or the like to obtain a transmission mask for charged beam exposure.

However, the conventional method of manufacturing a transparent mask is
As mentioned above and as shown in FIG. 3, there are many steps,
Further, it includes a polishing process that requires a long time and a bonding process that requires heating. For this reason, since it takes a lot of time and labor and the manufacturing time is long, the production cost becomes high, and the decrease in the yield due to the large number of steps is unavoidable.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to reduce the number of manufacturing steps, the manufacturing time required, and the yield as compared with the conventional method. A transparent mask can be manufactured easily and stably, that is, a transparent mask having high productivity can be manufactured.

[0006]

Means provided by the present invention in order to achieve the above-mentioned object is, that is, a transmission mask for a charged beam exposure in which a through hole having a predetermined pattern shape and arrangement is provided in a plane of a substrate. In the manufacturing method of,
That is, (a) a step of selectively removing the in-plane of the substrate to be the structure of the transmission mask for charged beam exposure by etching to a depth in the middle of the substrate thickness, (b) using a liquid capable of etching the substrate. At least the same side of the substrate as described above is coated with a surface to form a thin film for etching stop, and the opposite side of the substrate is coated with an opening pattern selectively left. To form a protective film for etching, (c) etching the substrate from the opening pattern on the opposite surface side of the substrate, and etching until the etching stop thin film is reached; A method of manufacturing a transmission mask for charged beam exposure, comprising the step (c).

Preferably, the substrate is a Si substrate, and the method for manufacturing a transmission mask for charged beam exposure described above is preferable.

It is preferable that the etching stop thin film is made of a Si compound, a boron compound, diamond, or a metal.

The material of the etching stopping thin film is Si
The method for producing a transmission mask for charged beam exposure according to claim 1, wherein the transmission mask is N, SiC, SiO ₂ , BN, or gold.

More preferably, the etching stopping thin film is a diamond-shaped thin film, and the method for producing a transmission mask for charged beam exposure is characterized in that.

Alternatively, in a transmission mask for charged beam exposure having through holes having a predetermined pattern shape and arrangement in the surface of the substrate, the transmission mask structure is an integrated structure. It is a transparent mask for.

[0012] Preferably, in the charged beam exposure transmissive mask, the transmissive mask has a thin film on a surface thereof.

More preferably, in the transmission mask for charged beam exposure, the transmission mask for charged beam exposure is characterized in that the integral structure is made of a conductive material.

Further preferably, in the transmission mask for charged beam exposure, the transmission mask for charged beam exposure is characterized in that the thin film is made of a conductive material.

Preferably, in the transmission mask for charged beam exposure, the transmission mask for charged beam exposure is characterized in that the material of the integral structure is Si.

In particular, when Si single crystal is selected as the substrate, the property of etching anisotropy due to its crystallinity can be utilized in the manufacturing process, whereby an opening having a tapered surface can be formed. It can be easily formed by etching. In addition, when the Si single crystal substrate is a silicon wafer which is often used in the manufacture of semiconductor integrated circuits, the number of defects is particularly small. It is convenient because it makes it easier to make expensive things.

The present invention will be described in more detail below with reference to the drawings. First, FIG. 1 is a sectional view showing an embodiment of a method of manufacturing a transmission mask according to the present invention in the order of steps. A resist is applied to the surface of a Si substrate such as a silicon wafer, and a resist pattern is formed in a portion which will be a transmission hole of a charged beam of a transmission mask by a usual photolithography or electron beam lithography means (FIG. 9A). Next, using the resist pattern as a mask, S
The i substrate is etched by a means such as reactive ion etching to a depth equal to a predetermined depth of the transmission hole, and then the resist pattern is peeled off to form a Si pattern on the surface of the Si substrate, which becomes a transmission hole for the charged beam. ((B) in the figure).

Next, the entire surface of the Si substrate in which the transmission holes are formed is covered with a thin film. The film forming method is not particularly limited,
For example, the low pressure CVD method is convenient because the entire surface can be coated at once. Here, the material of the thin film is
In the subsequent step of etching from the back surface side of the Si substrate, a material having a sufficiently low etching rate as compared with Si or being not etched is used. ((C) of the same figure).

Next, a resist is applied to the opposite surface side of the Si substrate, and a photolithography (which may be ultraviolet ray, electron beam or other electromagnetic wave) means is used to form an opening in the transparent mask. A resist pattern is formed. Then, the thin film is etched using this resist pattern as a mask. At this time, as a matter of course, the etching method may be selected and used as a means that has an etching property with respect to the thin film material and does not etch the resist pattern (or is extremely difficult to etch). Then, the resist pattern is peeled off (by means of reactive ion etching or the like) to form an opening pattern for etching protection of the Si substrate (FIG. 7 (d)).

Next, the Si substrate is etched with a KOH aqueous solution or the like, using the thin film portion of the etching protection opening pattern as an etching mask. Then, for the etching of the portion facing the transmission hole, the etching stop thin film formed at the bottom of the transmission hole (preliminarily, the etching rate is sufficiently lower than that of Si or a material that is not etched at all is selected. When it reaches the (formed thin film), it stops in a self-aligning manner, and only the thin film remains in the permeation holes ((e) in the same figure).

The etching of the Si substrate with a KOH aqueous solution or the like is terminated when the etching of the portion facing the transmission hole is stopped. After that, the target transmission mask structure can be obtained by removing the thin film remaining in the transmission holes. ((F) in the figure) When the thin film is an insulating film such as a SiN film, a conductive layer is formed after removing the thin film on the surface of the mask structure as usual to prevent electrification. To do. Further, as described later, when the thin film has conductivity, it is not necessary to intentionally form a conductive layer separately from this.

FIG. 2 is a sectional view showing a transmission mask of another embodiment by the manufacturing method according to the present invention.

Although the transmission mask for charged beam exposure of the present invention is completed in substantially the same manner as in FIG. 1, unlike the process described in FIG. 1, a thin film covering the entire surface of the Si substrate in which the transmission holes are formed. Is a conductive thin film such as a SiC film or a metal film, it is not necessary to remove the conductive film as shown in FIG. 1F, and the thin film may be left on the surface of the Si substrate.

When the surface of the Si substrate having the through holes is covered with a thin film, it may be difficult to cover the front and back simultaneously depending on the film forming method. In that case, the side of the through hole pattern is covered with the Si substrate. Then, the back side may be separately coated as an etching mask layer of the Si substrate. In this case, the thin films on the front and back sides do not necessarily have to be the same type of thin film.

[0025]

According to the manufacturing method of the present invention, the etching stop layer of the Si substrate is formed after first forming the pattern to be the transmission hole on the surface of the (Si) substrate. Therefore, the bonding process, which has been required in the past, which requires a long manufacturing time and a great deal of time and labor, is unnecessary, and the upper and lower Si substrate polishing processes, which are necessary for bonding, are also omitted. It will be possible. As a result, the number of steps and the manufacturing time can be significantly reduced. Further, in combination with this, and because the manufacturing is facilitated, the yield is improved.

[0026]

【Example】

<Example 1> 3-inch diameter 500 μm thick and plane orientation <100
A positive photoresist MP1400 was spin-coated on the surface of the Si wafer substrate of <> by 5 μm, and the transmission hole pattern on the photomask was transferred and formed by a known photolithography means. The exposure dose of the g-line at this time is 300 mJ /
It was cm ² . Next, using the resist pattern as a mask, the Si substrate was etched by an ECR (electron cyclotron resonance) ion beam etching apparatus to a depth of 20 μm. At this time, the etching gas is Cl ₂ and SF ₆
Microwave output is 200 with the addition of 10%
W. After that, the resist was removed by O ₂ plasma to form a Si pattern to be a transmission hole on the surface of the Si substrate.

Next, the Si substrate on which the through hole pattern is formed is put into a low pressure CVD apparatus, and a 1000 _x thick SiC _x film is formed on the entire surface of the Si substrate using C ₂ H ₂ and SiH ₂ Cl ₂ as source gases. did. After that, an opening pattern is formed on the back surface side of the Si substrate by a normal photolithography means, and the RIE is performed using the resist pattern as a mask.
After the SiC _x film on the back surface side was etched by (reactive ion etching), the resist was removed to form an opening pattern for etching protection of the Si substrate made of the SiC _x film.

Next, the Si substrate is etched with a KOH aqueous solution having a concentration of 30% and a liquid temperature of 90 ° C. using the etching protection opening pattern as a mask.
A membrane was formed by leaving only the iCN _x membrane. After that, the SiC _x film remaining in the transmission holes was removed while cleaning, and the transmission mask shown in FIG. 2 was completed.

Example 2 First, a Si pattern to be a transmission hole was formed on the surface of a Si wafer substrate having the same specifications as in Example 1 by the same method as in Example 1. Then, this Si substrate was put into an electron beam heating vapor deposition apparatus, and an Au film having a thickness of 1000 Å was formed on the surface of the transmission hole pattern side. After the back surface side of the Si substrate formed with the SiN _x film having a thickness of 1000Å by sputtering to form an etching protection opening pattern of the Si substrate made of the SiN _x film in the same manner as in Example 1.

Next, using the above etching protection opening pattern as a mask, 50% hydrazine (N _{2 at a} liquid temperature of 110 ° C.).
The Si substrate was etched by H ₄₎ solution. An aqueous solution of hydrazine anisotropically etches Si like an aqueous solution of KOH, but unlike the aqueous solution of KOH, the thin film of Au is hardly etched. Therefore, only the Au film was left in the transmission hole portion to form a membrane. After that, the Au film remaining in the transmission holes was removed while cleaning, and the transmission mask was completed.

When the edge shape of the transmission hole portion of the transmission mask according to <Example 1> and <Example 2> was inspected by an electron microscope, the transmission hole portion was covered with a thin film. As described above, there was little edge jaggedness due to the small edge along the surface surrounding of the single crystal Si. Regarding the conductivity, the surface area covered with the conductive film was larger than that in the case of the conventional technique, and good results were obtained because the insulating film was not included in the middle. In addition, good dimensional accuracy and hole shape were obtained. In addition, the manufacturing method is simpler than that of the conventional technique, which leads to a reduction in time. In general, the required manufacturing time was short, the number of steps was small, and a good quality transparent mask could be easily and stably manufactured.

[0032]

As described above, according to the method of manufacturing a transmission mask of the present invention, a pattern portion to be a transmission hole is first formed on the surface of a Si substrate, and then an etching stop layer of the Si substrate is formed. Since this is performed, the bonding step which has been necessary in the past is unnecessary, and therefore the polishing step of the upper and lower Si substrates for bonding can be omitted. The laminating step and the polishing step not only consume a long manufacturing time but also increase the number of steps, and also take time and labor, which causes a reduction in yield. Depending on the film formation method, the etching stop layer of the Si substrate and the etching mask layer can be formed at the same time, or if a conductive film is used as the etching stop layer, the formation of a new conductive layer becomes unnecessary. come.

As a result, the number of steps and the manufacturing time can be greatly reduced, and a great effect can be obtained in improving the yield and reducing the production cost. As a result, it is possible to easily and stably manufacture a transmissive mask having a smaller number of manufacturing steps and a shorter manufacturing time than before, and a high yield.
That is, it was possible to provide a method for manufacturing a transmission mask that can exhibit high productivity in its manufacture.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a method of manufacturing a transmission mask according to the present invention in the order of steps using sectional views.

FIG. 2 is an explanatory view showing another embodiment of the method of manufacturing a transmission mask according to the present invention in the order of steps using sectional views.

3A to 3C are explanatory views showing an example of a method of manufacturing a transmission mask according to a conventional technique, in order of steps using sectional views.

[Explanation of symbols]

 1 ... Silicon substrate 2 ... Resist pattern 3 ... Transmission hole 4 ... Thin film 4 '... Etching stop layer 5 ... Opening pattern 6 ... Transmission mask structure 7 ... Conductive layer 8 ... Supporting silicon substrate 9 ... Upper silicon substrate 10 ... Insulating layer 11 ... Bonded silicon substrate 12 ... Mask layer 13 ... Opening pattern 14 ... Transmission hole 14 '... through hole 15 ... opening 16 ... conductive layer

Claims (10)

[Claims] 1. A method of manufacturing a transmission mask for charged beam exposure, wherein a through hole having a predetermined pattern shape and arrangement is provided in a surface of a substrate, in the following step: (a) Structure of transmission mask for charged beam exposure. A step of selectively removing the in-plane of the body substrate by etching to a depth in the middle of the substrate thickness, (b) using a material having resistance to a liquid capable of etching the substrate, A step of covering the surface of the same side of the substrate as an etching stop thin film and a surface of the opposite side of the substrate for selectively leaving an opening pattern to cover the surface as a protective film for etching; Etching the substrate from the opening pattern on the opposite surface side of the substrate and etching until reaching the etching stop thin film, and comprising at least the steps (a) to (c) above. Method for producing a charged beam exposure transmissive mask that. 2. The method for manufacturing a transmission mask for charged beam exposure according to claim 1, wherein the substrate is a Si substrate. 3. The method for manufacturing a transmission mask for charged beam exposure according to claim 1, wherein the etching stopping thin film is a Si compound, a boron compound, diamond, or a metal. 4. The material of the etching stopping thin film is Si
The method for producing a transmission mask for charged beam exposure according to claim 1, wherein the transmission mask is N, SiC, SiO ₂ , BN, or gold. 5. The method of manufacturing a transmission mask for charged beam exposure according to claim 1, wherein the etching stopping thin film is a diamond thin film. 6. A transmission mask for charge beam exposure, which has through holes having a predetermined pattern shape and arrangement in a plane of a substrate, wherein the transmission mask structure is an integral structure. Transmission mask. 7. The transmission mask for charged beam exposure according to claim 6, wherein the transmission mask has a thin film on its surface. 8. The transmission mask for charged beam exposure according to claim 6, wherein the integral structure is made of a conductive material in the transmission mask for charged beam exposure. 9. The transmission mask for charged beam exposure according to claim 7, wherein the thin film is made of a conductive material in the transmission mask for charged beam exposure. 10. The transmission mask for charged beam exposure according to claim 6, wherein the material of the integrated structure is Si.